1. Field of the Invention
The present invention relates to a thermal printer and printing method. More specifically, the present invention relates to a thermal printer and printing method capable of printing a thermal recording paper with compensation of slip thereof.
2. Description of Related Art
Thermal printers use a special type of paper, (hereinafter, referred to as “thermal recording paper”) which reacts to the application of heat to display a predetermined color, and ink ribbons, which react to the application of heat to transfer a predetermined color to a regular sheet of paper to print thereon. In the case where ink ribbons are used, a driving device is required, so that the construction of the printer is more complicated and the cost is higher. In addition, the ink ribbons need to be replaced regularly. Thus, a printing cost per sheet of paper is high.
Referring to FIG. 1, a thermal recording paper 10 includes a base sheet 11, and predetermined colors of ink layers provided at both surfaces, such as the first and second surfaces 10a and 10b of the base sheet 11. The ink layers are typically layers of different colors. For example, yellow Y and magenta M layers are provided on the first surface 10a one after another, while a cyan C layer is provided on the second surface 10b. Preferably, the base sheet 11 is a transparent material. Reference number 13 indicates a transparent layer or a reflective layer. An example of the thermal recording paper 10 is described in U.S. Pat. No. 6,801,233.
In a conventional thermal printer that uses the thermal recording paper 10, a thermal printhead (TPH), which is used to generate the image on the thermal recording paper 10, has thermal transfer elements that are arranged at a predetermined resolution in a direction perpendicular to a feeding direction of the thermal recording paper.
FIG. 2 is a diagram of a conventional thermal printer.
The thermal printer includes a feed roller 2 for feeding the thermal recording paper 10, a platen 3 for supporting one surface of the thermal recording paper 10, and a TPH 4 for forming an image over the thermal recording paper 10 supported by the platen 3. An idle roller 5 causes the thermal recording paper 10 to pass between the idle roller 5 and the feeding roller 2 to be closely adhered to the feeding roller 2.
Further, in the thermal printer, a paper fed by a thermal or mechanical load may slip. In particular, the amount of slip may be different for each side or surface of the thermal recording paper, so that image misalignment between each surface may occur, which will degrade image quality.